This invention relates generally to the coloring of dental restorations to match the color of a patient's existing teeth. More particularly it relates to a method of coloring bakeable porcelain dental restorations through the application of a pigment of low temperature procelain-fusable powder dispersed in a substantially clear vaporizable cureable carrier liquid.
It is desireable to match the color of a dental restoration to the color of the patient's existing teeth for aesthetic reasons and to encourage the patient to use the prosthesis. Tooth color varies not only from patient to patient, but also from tooth to tooth on a single patient, and may even vary on a single tooth from side to side or top to bottom. These variations arise from, among other things, smoking, drinking of tea or coffee, variations in dental hygiene or diet, physical injury, or orthodontics. In addition, the teeth of younger patients are generally lighter in color than the teeth of older patients.
In the past, the dentist or technician would attempt to match the color of the existing teeth to one of a finite number of sample colors supplied by a dental laboratory. This limited selection made it possible to approximate the desired color, but very rarely was the dentist able to duplicate the same intensity or hue. Moreover, the color selected was usually uniform over the entire tooth, eliminating the possibility of different shadings or hues for a single tooth. A still further disadvantage was that the laboratory technician would then attempt to duplicate the dentist's chosen color on the actual restoration at a later date, in a laboratory remote from the dentist's office, and without the patient present. All of these disadvantages contributed to undesireable nonuniform and inaccurate color match-ups. Moreover, variations in the type or color of the light used by the dentist and technician, and the position in the mouth of the restored tooth, resulted in still further color variations. Thus, it sometimes became necessary for the patient to visit the dental laboratory on several occasions over a period of several days or weeks for a trial and error method of coloration. This was time consuming, costly, and exasperating for both the patient and dentist.
The coloring of porcelain dental restorations was accomplished in the past by applying an appropriate amount of pigment in a water soluble solution and then baking the restoration to permanently impart the color. If, after baking, the color had to be darkened or altered by the addition of more pigment, then the steps had to be repeated as often as necessary until a satisfactory color was obtained. However, if the color was too. dark, or the hue could not be altered by the addition of color, an expensive restoration was ruined. Thus, this task required great skill and experience. These problems were heightened by the use of a water solution because the presence of moisture or saliva on the tooth often destroyed or mottled the coloration, and in some instances the application of subsequent coatings before baking would remove, dissolve or otherwise alter the earlier applied coatings. Moreover, coatings that are water soluble often rub off with excessive handling, and they cannot be used in the mouth, making a correct color match at the dentist's office more difficult.
The coloring of acrylic or plastic restorations required the application, to a finished restoration, of a stain or shading compound dissolved in water or a solution that evaporates at room temperature. Although baking is not necessary, these colors are permanent and must be ground off if the color is too dark or cannot be corrected by the addition of more color or stain. In addition, the aforenoted problems associated with moisture and water soluble coatings also apply to acrylic restorations.